In a surface-treatment device such as a shot-peening machine, it is preferable to set optimal projection conditions of abrasive particles to be projected by a projection device based on the shape of an article to be processed and the area of the surface to be processed, etc. The projection conditions of the abrasive particles in this context include the area to be shot-peened or the distribution of the shot-peening, as well as the amount and the velocity of the abrasive particles to be projected. To this end, Japanese Patent Early-Publication No. 1996-323629 (prior art 1), by the assignor of the present application, discloses a method and an apparatus for regulating the distribution of the shot peened based on the article to be processed when the quantity and the velocity of the abrasive particles to be projected are changed based on that article to be processed.
As another prior-art publication, a shot-peening machine is disclosed in Japanese Patent Early-Publication No. 1989-264773 (prior art 2). It limits the distribution of the shot peened by projecting the abrasive particles of the shot peened in a distribution that is wider than the surface to be processed and by providing a so called vane as a liner between the projection device and the article to be processed, to limit the range of the projection of the abrasive particles.
Further, the apparatus disclosed in Japanese Patent Early-Publication No. 2003-340721(prior art 3) is configured to concentrate the distribution of the abrasive particles within a predetermined range by shortening the length of a blade so as to maintain the constant direction of the projection without using a vane.
However, in the disclosures of prior art 1, deciding the distribution and the velocity of the projection necessitates a centrifugal projecting device that actually projects the abrasive particles to the article to be processed to confirm the distribution and the velocity of the abrasive particles based on the result of the actual projecting. Therefore, it necessitates time to obtain an accurate relationship between the optimum processing and the distribution of the projection. Desirably, the centrifugal projecting device will provide for distribution of the projection that is best suited for articles to be processed and for the processing method in the centrifugal projection device, because saving energy and an efficient projection are needed. From this viewpoint, it is inconvenient to require time to understand an accurate relationship between the optimum processing and the distribution of the projection.
Moreover, because the vane is worn out by the collisions with the abrasive particles, thus a vane that restricts the range of the projection may change this range in the device of prior art 2. So it might cause the quality of the articles for processing to decrease. Therefore, it is frequently necessary to exchange a vane. Moreover, because the abrasive particle is reflected from the vane, and the particle rebounds in the inner wall of the projection chamber, the protection from wear from the wall of the projection chamber is also necessary.
In contrast, in the device of prior art 3 the difference is caused at the position of the blade where the supply of the abrasive particles is not constant, each part of the abrasive particles collides, and the distribution of the projection diffuses though the length of the blade and is extremely shortened, to concentrate the distribution of the projection to a predetermined range. Therefore, it is easy to receive the effect when the supply of the abrasive particles is unstable. Moreover, the slower the velocity is of the rotation of the impeller, possibly the efficiency of the treatment decreases, because abrasive particles that are dispersed outside of the impeller without colliding with the blade are generated. In addition, because it greatly affects the accuracy of the distribution of the projection when the shape of the blade changes by the wear, and because the blade is worn out by the collisions with the abrasive particles, it is necessary to frequently exchange the blades.
Accordingly, one object of the present invention is to provide a method and a system for estimating information on the state of the projection of abrasive particles projected by a projection machine to reduce operating costs and the time to know conditions involving the state of the projection of the abrasive particles to define information on a specified state, e.g., at least the distribution of the projection or the velocity of the projection.